Here is my take Harold. And this comes from Paul and some other folks that train dogs as well as from reading John's book. I don't know if it's interdigital or some other scent or pheromone but there is definitely something a fatally wounded deer gives off or it's a combination of several scents that really gets my dog fired up. I can get a good idea in a couple hundred yards by the way the dog acts if we are gone be successful or if we're just walking around in the woods. You got a better relationship with Otis than I do with mine maybe ask him. Lol. I had 2 the other day one was shot dead square in the but first couple hundred dog didn't really get excited until we found a wound bed with a couple clots in it from there to the end he acted like a completely different dog as far as how he behaved and worked. Went to the next one which turned out to be a backwhack and he wasn't at all interested in what was goin on so we went hiking in the woods and never found anything he wanted to mess with. I don't know if that's interdigital or what or if just something the dogs know that we don't but I do know there is something